#include "shoes.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int n;
struct Fenw {
int n; vector<int> bit;
Fenw(int N) {
n = N;
bit.assign(n, 0);
}
int g(int i) {
return i & (i+1);
}
int h(int j) {
return j | (j+1);
}
int query(int idx) {
int res = 0;
while (idx >= 0) {
res += bit[idx];
idx = g(idx) - 1;
}
return res;
}
void update(int idx, int delta) {
while (idx < n) {
bit[idx] += delta;
idx = h(idx);
}
}
void update(int l, int r, int delta) {
update(l, delta);
update(r+1, -delta);
}
};
ll count_swaps(vector<int> s) {
n = s.size() / 2;
ll minimum = 0;
auto fenw = Fenw(2*n);
map<int, set<int>> shoes;
set<int> used;
for (int i = 0; i < 2*n; i++) {
shoes[s[i]].insert(i);
}
for (int i = 0; i < 2*n; i++) {
if (used.count(i)) continue;
int size = s[i];
int partner = *shoes[-size].begin();
used.insert(i); used.insert(partner);
shoes[size].erase(i); shoes[-size].erase(partner);
int dist = (fenw.query(partner) + partner) - (fenw.query(i) + i) - 1;
if (size > 0) dist++;
minimum += dist;
fenw.update(i, partner, 1);
}
return minimum;
}
